Process for introducing an optical cable into solid ground

ABSTRACT

The invention relates to a process for introducing an optical cable, in the form of a microcable or minicable ( 1 ), in solid ground ( 17 ) with the aid of a laying unit ( 23 ). The microcable or minicable ( 1 ) used for this purpose comprises a homogeneous and pressurized-water-tight tube ( 8 ) which has an external diameter of from 2.0 to 10 mm and into which optical waveguides ( 3 ) are introduced.

The invention relates to a process for introducing an optical cable,consisting of a tube and optical waveguides introduced therein, intosolid ground with the aid of a laying unit.

DE-A1-41 15 907 discloses a cable-laying plough for laying cables in theground, in particular in the ground under water. In this case, the bladeof the cable-laying plough has arranged in front of it a rotatingcutting wheel which, in addition, is made to vibrate vertically, withthe result that hard objects located in the region of the trench whichis to be excavated may thus also be broken up thereby. This cable-layingplough excavates relatively wide trenches by displacing the soil withthe aid of the plough blade. Such machines are used, in particular, incoastal areas and under water using corresponding control devices. Forlaying operations in the ground, the material is usually removed over awidth of from 60 to 100 cm and a cable-laying depth of approximately 70cm, with the result that the outlay for the laying operation isrelatively high.

Furthermore, DE-A1-30 01 226 discloses a line network for transmittingsignals, the signals being passed through fibre-optic cables which arelaid in a network of pipes or ducts of an existing supply system. Inthis case, however, fixed cable-laying routes are predetermined, andinlets and outlets for the cable which is to be laid have to be providedin a suitable manner therein.

Alternatively to this, use may also be made, over short distances, ofso-called drilling or jetting processes in which a tube is introducedhorizontally into the ground. The high outlay for laying machines andmaterial is also disadvantageous here.

JP-A-61 107 306 discloses an optical waveguide which is provided with ametal tube in order to increase tensile strength. The optical waveguideis provided with a sheath of vinyl, nylon or urethane, these materialshaving elastic properties and thus protecting the optical waveguidemechanically against external influences. In order to increase thetensile strength, a metallic tube is also applied, loosely at first.Then the tubes are stretched and thus secured to the sheathed opticalwaveguide.

FR-A-2 677 137 discloses a repair method for optical cables which arecomposed of a tube and optical waveguides running therein. At thedefective point, an adapted tubular element is inserted, to which theends of the defective tube are connected again, the defective pointbeing bypassed.

EP-A-0 553 1991-A discloses a repair method for conventional opticalcables, two cable sleeves being used in which the connections are madebetween the optical waveguides by means of an intermediate cableelement.

The object of the present invention is to provide a process forintroducing an optical cable in which the outlay for the layingoperation can be reduced, it also being intended that the outlay for theoptical cable system used be coordinated with the laying method. The setobject is achieved according to the invention, by a first process of thetype explained in the introduction, in that the optical cable used is amicrocable or minicable having an external diameter of the tube of 2.0to 10 mm, preferably 3.5 to 5.5 mm, the tube being homogeneous andpressurized-water-tight, a laying channel with a width of 4.5 to 12 mm,preferably 0.7 mm, which is adapted to the diameter of the microcable orminicable, being introduced with the laying unit into the solidunderlying laying surface, the microcable or micro[sic]cable beingintroduced into the laying channel by means of a feed element and beingheld at a constant laying depth, the laying channel being filled withfilling material using a filling device which is moved along after theinsertion of the microcable or minicable.

The object which has been set is thus achieved in accordance with theinvention planning to a second method of the type mentioned at thebeginning in such a way that a microcable or minicable with an externaldiameter of the tube of 2.0 to 10 mm, preferably 3.5 to 5.5 mm ispressed into utility lines for sewerage, gas or water, which have beenleft open, using a laying unit.

The object which has been set is achieved according to the inventionusing a third method of the type mentioned at the beginning in that theoptical cable used is a microcable or minicable with a diameter of thetube of 2.0 to 10 mm, preferably 3.5 to 5.5 mm, which is inserted intoexisting, active utility lines for sewerage gas or water using a layingunit.

A great advantage of the process according to the invention is that onlya relatively short amount of time is taken for the laying operation,with the result that it is used particularly wherever long-term hold-upsare undesirable. This is the case, for example particularly when layingnew or additional cables, when the laying operation has to be carriedout in urban areas with heavy traffic. Blocking off or diverting is tobe avoided as far as possible. The operations of cutting, laying andsealing the channel can take place directly one after the other, theseoperations expediently being carried out all in one go by a multipurposemachine. In this manner, the traffic disruption is barely greater thanthat caused by a road sweeper. There is also such a need, for example,when all the laid pipes, cable ducts or pipelines have already hadcables laid in them, it then being possible to splice onto the newlylaid cables without interruption. Tubular mini communication cables,which are referred to as microcables or minicables, are particularlysuitable for this purpose. These newly laid minicables or microcablesmay preferably be connected to form a redundant overlay network.

According to the invention, such a minicable or microcable comprises ahomogeneous and pressurized-water-tight tube of very small diameter offrom 2.0 to 10 mm, preferably 2.2 to 5.5 mm. These tubes have a wallthickness of from 0.2 to 0.4 mm. The most favourable values as regardsthe buckling resistance are achieved with a wall thickness to anexternal diameter ratio of between 1/5 and 1/20, preferablyapproximately 1/10. The smallest internal diameter of the tube used is1.8 mm. This tube may be produced from metal, for example fromchromium-nickel-molybdenum (CrNiMo188) steel, aluminium alloys, copperor copper alloys or from plastic, for example with reinforcement insertsconsisting of carbon fibres, glass fibres, or a sintered carbon-fibrestructure. These tubes may be extruded, welded, folded or bondedlongitudinally at the overlap. The optical waveguides are thenintroduced into the tube either after the empty tube has been laid or atthe factory. The optical waveguides can be blown in or jetted in.

The tubular minicable can be introduced into solid ground by varioustypes of process according to the invention:

1. The laying may be carried out by means of a laying machine which hasa cutting wheel, with the aid of which a narrow laying channel having awidth of from 4 to 12 mm, preferably 7 mm, and a depth of from 50 to 100mm, preferably 70 mm, is cut in the ground, in particular in an existingroadway.

2 Such a minicable may also be forced into disused supply lines(wastewater, gas, water). Disused pipelines of utility companies areparticularly suitable for a laying operation. They correspond largelywith the supply network planning to be set up. Even if the disused pipesare in bad condition, it is possible to introduce the thin metal tubesof the minicable since they are pressed in in the longitudinal directionand pass through obstructions such as dirt, rust and the like. Theminicable does not buckle in pipes since it is supported by the disusedsupply line. After leaving these pipelines, the laying operation mayalso be continued with the aid of other laying processes.

3. It is likewise possible for a minicable to be pushed into existing,active supply lines (wastewater, water). The function of the supplylines is barely impaired to any extent at all in this case. The tubularminicable is resistant to pressurized water, wastewater and corrosion.Gnawing by rodents can be ruled out due to the large wall thickness ofthe metal tube. It can be assumed that the optical-waveguide networkwhich is to be installed corresponds with the existing supply network.Earthworks may thus be reduced to a minimum. Appropriate fittings whichmake it possible to lift the minicable out of the supply lines are to beprovided at the appropriate locations.

4. Minicables may likewise be introduced into the ground byearth-displacement or jetting processes. In this case, first of all thetube of the minicable is introduced, as a mechanical protection, intothe ground. Expediently, the fibre conductors, or very thin blownfibres, are subsequently blown or jetted in. In order to minimize thefriction during the blowing-in operation, the tubes, which are producedwithout seams and are smooth on the inside, are coated with a plasticlayer, e.g. PTFE. This layer is, for example, deposited from a PTFEsuspension when the metal tube is heated correspondingly. Moreover, thislayer protects against corrosion and soiling of the tube interior.Earth-displacement and pressing-in operations in which a drilling headwith a bevel rotates constantly are known. If the drilling head does notrotate, the drilling body is deflected in accordance with the bevel. Itis thus possible to bypass obstructions. A water jet at very highpressure may, for example, force away small stones. The tube cuts orjets its way through the ground and assists the advancement of thepressing-in process. Moreover, the water pressure can move a piston inthe drilling body. The thrust-like movement of the drilling head thenbreaks through obstructions more easily and reduces the static frictionduring the drawing-in operation.

By elastic expansion of the tube, the wall friction with respect to theearth can be reduced further. For this purpose, an outlet valve wouldhave to be provided at the end of the tube.

Using the tubular minicable according to the invention, then, results inparticular advantages, as follows. The laying or introduction takesplace with the aid of a hollow tube, which, as cable, is alreadyprovided with optical waveguides; however, it is also possible for theoptical waveguides to be drawn in subsequently. Appropriate selection ofthe wall thickness ensures sufficient protection against mechanicalloading, corrosion and gnawing by rodents. Moreover, the tube has a highstability to transverse compressive stress. For lengthening and thinningthe tube, use may be made of methods, which are known per se, withcutting clamping rings or a crimping process. For lengthening a tubeconsisting of copper, connection by cold pressure welding is possible,for example. Otherwise, the tube can be processed like a normalinstallation pipe, these methods relating to bending, provision offittings, branchings and inlets in sleeves. Also suitable for thispurpose are cylindrical metal fittings into which the minicable can beintroduced tightly. When the laying operation is taking place from thesurface of the ground, the surface is only minimally broken up, which isparticularly advantageous for laying operations in roads. Moreover, as aresult of the rigidity, pulling and pushing the minicable is possibleand helpful in the laying operation. Due to the small diameter of such aminicable, the earth displacement is also particularly low, it beingpossible for the earth to be displaced when the cable is pressed ordrawn into the surrounding earth.

A tubular microcable or minicable is particularly suitable for laying ina roadway or in footpaths since the roadway formation is barely brokenup by the necessary channel. All that is necessary in order to ensurethe safety of such a cable is a channel having a width of 4 to 12 mm anda depth of approximately 70 mm. In this case, the channels for receivingthe cables should, as far as possible, only be provided on the sides ofthe road since stressing is at its lowest here. The channel which hasbeen introduced is refilled after the introduction of the cable or ofthe tube and is sealed against the penetration of surface water. Thissealing must not produce any cavities in which surface water cancollect. The roadway surface can be restored in a simple manner. Allthat is required during repair work is that, when the road surface iscut away, the minicable or microcable which has already been laid is notdamaged.

A laying operation using a microcable and the corresponding layingprocess according to the invention produces considerable reductions inthe costs for the laying method, this resulting in a considerablereduction in the overall line-laying costs in the case of a newinstallation. Moreover, the operational reliability is increased byredundant routing.

It is also advantageous that annular network structures with variousconnection possibilities can be formed from former rigid, star-shapedbranching networks. A flexible, intelligent network design is obtainedin this manner, it being possible for microcables to be switched in withthe aid of optical switches. A pigtail ring with optical switching, inwhich optical fibres could be routed as far as the subscriber, wouldthus be possible. It is highly advantageous that subsequent layingoperations in roads, footpaths, cycle paths, curbstones and the like arepossible with a low degree of outlay. Consequently, a technical conceptmay be adapted in a simple manner to the wishes of the operator, itbeing possible to utilize the existing infrastructure (wayleaves, andpipes for wastewater, gas, district heat, etc.) It should also be notedhere that, in comparison with the standard method, this method can savea large amount of time.

Various points should be noted when a laying channel is provided in anasphalt surface of a federal road which is made up of a top surfacecourse of 4 cm, a binder course of approximately 8 cm and a base courseof from 10 to 15 cm. The proportion of bitumen decreases towards thebase course, but the coarse-grained fillers increase. However, thebitumen ensures the cohesion within the individual layers. Duringcutting as far as the asphalt base course, the laying channel is, then,dimensionally stable, with the result that no material caves in and theoverall upper road structure remains intact. During cutting, it is notpermitted to cut through the bitumen base course as far as theanti-frost layer of the substructure since this may result in weakpoints in the series of asphalt layers, which weak points could break upthe layer formation and result in damage to the road within a shortperiod of time. However, if the minicable is laid in a water-tight andfrost-resistant manner, the soil mechanics are not influenced by thisintervention. However, modern roads are frost-resistant since thecrushed-stone substructure bears and absorbs loads. This dischargesgravitational water into the earth or into drain pipes, and a sealed,intact surface course does not let in any surface water. Frost damagecannot therefore occur. This minimum laying-channel width andvibration-free cutting means that the mechanical structure of the roadremains intact. Directly after the laying operation, the laying channelis closed off again in a frost-resistant manner by a hot-melting bitumenor by a fusible preformed bitumen filler.

However, very heavy traffic may result in additional consolidation andflow in the upper structure of the road (lane grooves, shoulder). It isthus recommended that the laying channel is foam-filled with a curableplastic around the minicable directly after the latter has been laid.After curing, the foam filling achieves a compressive stressabilitywhich is sufficient for further distributing the load of the carriagewaysurface uniformly. Cavities and interstices between the minicable andthe laying channel are filled, without leaving any cavities which couldreceive any surface water which may penetrate and propagate this surfacewater along the minicable.

Vibrations due to the heavy traffic are absorbed by the foam filling andare not passed on to the minicable. Relatively small occurrences of theearth subsiding may also be compensated for by the elastic foam, withthe result that such irregularities in the bitumen base course would notresult in the failure of the minicable due to bending of the tube orfibre elongation.

For a minicable according to the invention, compressed-gas monitoringand monitoring with a liquid, for example, are also possible. Theminicable may thus also be filled with a liquid which, in the case ofthe tube having a defect, escapes and resinifies under the action ofair. This ensures a kind of “self-healing”.

Moreover, the minicable is interception-proof since the opticalwaveguides cannot be bent. The minicable is stable with respect totransverse forces, has a high tensile force, is compact and, on accountof the small diameter, has a relatively low weight and little friction.The tube, which acts as the cable sheath, also assumes, at the sametime, the tensile-force function of the otherwise customary centralelement in this high-strength cable with very low expansion, there is noproblem in respect of excess lengths when the minicable is drawn in andlaid. This configuration gives a higher strength in comparison with anormal cable with a conventional plastic cable sheath, with the resultthat it is also possible to work with considerably larger drawing-inforces. Moreover, straightforward earthing is possible in the case ofthe metal embodiment. If use is made of a plurality of tubes which areinsulated with respect to one another, the metal cross-section may alsobe used for supplying power to active components. By using metal tubes,it would also be possible for overhead cables to be of a considerablymore straightforward construction. A supporting element (e.g. amessenger wire) could then be dispensed with since the metal tubesassume this function. In addition, such a minicable ispressurized-water-tight, gas-tight, forms a water vapour barrier andgives protection against the gnawing of rodents. Furthermore, it isfire-resistant, has excellent heat-dissipation properties and isresistant to aging and corrosion.

The flexibility of the minicable or of the tube can be improved by agrooved sheath.

Further developments of the invention are given in subclaims.

The invention will now be explained in more detail with reference to 57figures.

FIG. 1 shows a construction of the tubular microcable or minicable witha capping.

FIG. 2 shows, schematically, a longitudinal section through the minitubewithout optical waveguides.

FIG. 3 shows, schematically, the laying operation for a minicable.

FIG. 4 shows the forcing-in process for a minicable.

FIG. 5 shows the pushing-in process for a minicable.

FIG. 6 shows the jetting process for a minitube.

FIG. 7 shows the method of laying the tubular minicable with the layingchannel already filled again.

FIG. 8 illustrates the cross-section of a road-surface with a layingchannel cut therein.

FIG. 9 shows the laying channel which has already been filled in.

FIG. 10 shows a U-shaped holding-down device for microcables in thelaying channel.

FIG. 11 shows a rivet-like metal bolt as holding-down device forminicables.

FIG. 12 shows a plan view of the sketched construction of a bendingdevice for thin-walled tubular microcables or minicables.

FIG. 13 shows the laying channel filled with hot bitumen and colouredglass particles.

FIG. 14 shows a length-equalizing loop in a longitudinal section throughthe road surface along a cut laying channel.

FIG. 15 shows a sleeve for a tubular microcable or minicable.

FIG. 16 shows a laying channel for laying a minicable or microcable.

FIG. 17 shows a widened laying channel before the resulting central webhas been broken out.

FIG. 18 shows the cross-section through the cutting-wheel arrangement ofthe laying unit.

FIG. 19 shows a spacer ring with rectangular grooves on its outercircumference.

FIG. 20 shows a spacer ring with sawtooth-shaped grooves on its outercircumference.

FIG. 21 shows the arrangement of brushes on the outer circumference ofthe spacer ring.

FIG. 22 shows the lateral offset of hard-metal teeth.

FIG. 23 shows a laid microcable with a tension-resistant release elementlaid in addition.

FIG. 24 shows a laid microcable with a filling profile as filling meansfor the laying channel.

FIG. 25 shows the electric connection of two minicables or microcablesvia a metallic cable sleeve.

FIG. 26 shows an insulated microcable with an insulated power cable.

FIG. 27 shows a non-insulated microcable with an insulated power cable.

FIG. 28 shows a non-insulated power cable with an insulated microcable.

FIG. 29 shows an insulated microcable with a cable holding-down device.

FIG. 30 shows a microcable with an additional cable in a commoninsulation.

FIG. 31 shows an embodiment according to FIG. 30, but with a webconsisting of insulation material located in between.

FIG. 32 shows two electrically insulated minicables or microcables.

FIG. 33 shows two minicables or microcables within a common insulation.

FIG. 34 shows a sketch of the process being carried out.

FIG. 35 shows the laying of the minicable or microcable withmagnet-containing cable holding-down devices.

FIG. 36 shows U-shaped, magnetic cable holding-down devices in thelaying channel.

FIG. 37 shows bar-like, magnetic cable holding-down devices in thelaying channel.

FIG. 38 shows bar-like cable holding-down devices which are lined up ina row on support filaments.

FIG. 39 shows a cable holding-down device which has its ends clamped onsupport filaments.

FIG. 40 shows a cable holding-down device which is fitted into a supportsheet.

FIG. 41 shows the laying of the microcable with electronic signalgenerators as holding-down devices.

FIG. 42 shows a chip which can be freely programmed from the outside, isfitted along the microcable and is lined up on support filaments.

FIG. 43 shows a programmable chip which is accommodated in a sleeve.

FIG. 44 shows a defective microcable.

FIG. 45 shows a plan view of the repair location.

FIG. 46 shows a cross-section of the repair location.

FIG. 47 shows a unit for exposing the laying channel.

FIG. 48 shows a foam-rubber element introduced in the longitudinaldirection.

FIG. 49 shows a laying channel with a profile body of circularcross-section before the compression operation.

FIG. 50 shows the laying channel after it has been closed off.

FIG. 51 shows a laying unit.

FIG. 52 shows a longitudinally slit, annular profile body which isfitted on the microcable.

FIG. 53 shows the arrangement according to FIG. 52 after the layingchannel has been filled.

FIG. 54 shows a profile body with longitudinally running free ducts.

FIG. 55 shows the profile body according to FIG. 54 in the layingchannel.

FIG. 56 shows a profile body which is coated with a sealant.

FIG. 57 shows an exemplary embodiment for heating the sealant during thelaying operation.

FIG. 58 shows the covering profile after the laying operation in thelaying channel.

FIG. 59 shows a cross-section of the mechanical influence of the pointedobject.

FIG. 60 shows a front view of the influence of the object on thecovering profile.

FIG. 1 shows the construction of a tubular microcable or minicable 1,the cable end 2 being provided with a drawing-in or drilling tip 5. Thearrow 6 indicates the drilling movement or advancement direction of thedrilling head. Running in the interior of the minicable 1 are theoptical waveguides 3, which may be introduced either at the factory orafter the laying operation. The outer surface of the minicable isprovided with a surface protection 4.

FIG. 2, then, shows the tube 8 of the minicable 1, in the interior ofwhich, that is to say in the central duct of which, optical waveguideshave not as yet been provided. In this case, the said central ductserves initially as a pressurized jetting duct for the laying operation.Thus, an appropriate medium, for example a suitable liquid, is injectedunder pressure, with the result that the earth is jetted out anddisplaced at the end 11 of the minicable. In addition, rotating movementof the drilling tip 10 in accordance with the arrow directions 12 canincrease the action. Following the laying operation, the opticalwaveguides or so-called blown-fibre conductors are then introduced intothe tube 8 of the minicable 1. On the left-hand side of the minicable,the letter P symbolizes the pressure, required for the jetting process,by which the medium is injected. If a valve is provided at the end ofthe drilling tip 11, corresponding control allows the liquid to bepulsed out under pressure. At the same time, the tube 8 could increaseand decrease in diameter in an oscillating manner, this eliminatingstatic friction with respect to the earth.

FIG. 3 displays a method of laying a tubular minicable in the sand,gravel, earth or asphalt with the aid of a laying unit 23, by means ofwhich a laying channel 19 is cut in the surface 14 of the ground 17.Covering slabs or cobble stones are removed beforehand. The machinecomprises a linkage 22 on which the required individual parts arecombined to form a unit. All the process steps are coordinated with oneanother. In the case of the laying channel 19 which is to be provided inthe laying direction 21, a cutting wheel 15 with corresponding cuttingteeth, which cut a thin laying channel 19 with steep side walls, leads.The width of the laying channel is just sufficient to receive thetubular minicable 1 and the laying blade 18. Said laying blade 18protects the side walls against caving in, guides the minicable 1 alongand, via a cable-fixing means 7, holds constantly at the laying depththat end of the cable which is to be laid, the minicable or microcable 1being fed from a ring, which is wound up on a laying reel 24, viaadvancement rollers 25. A jetting rod 16 compacts the deposited earth orfilling sand 20 behind the laying blade 18. This operation takes placedirectly after the excavating operation. It is thus not possible for theside walls of the laying channel in the region 13 of the laying machineto cave in. Surrounding earth will not cave in, with the result that thesurface 14 will not sink. The cutting wheel 15, the laying blade 18 andthe jetting rod 16 together form the laying unit 23 and are connectedrigidly to one another via a linkage 22. A drive 30 moves the entirelaying unit 23 continuously in the laying direction 21. The end 29 ofthe minicable is introduced at the beginning of the laying channel 19via a so-called laying bow 26 and a laying thimble 27. The centralconnection 28 for pressurized water jetting is provided on the layingunit 23. Following the laying operation, the road surface is restored orsealed.

Such laying operation gives particular advantages since all cable typeswith a small diameter can be laid, the outlay being essentially lowerthan for conventional laying with a wide trench. During the layingoperation, the minicable is both drawn by the laying blade and guidedalong by the advancement rollers. Pulling and pushing of the minicableduring the laying operation can reduce the tensile loading. Moreover,the tubular design of the minicable prevents buckling during laying inthe channel. Excavating, laying, filling in and sealing the ground takeplace directly one after the other and constitute a preciselycoordinated operational sequence. The cable is supported by the verynarrow laying channel, with the result that the risk of buckling isreduced. Moreover, in the case of such a narrow laying channel, the soilmechanics and the surface of the ground are only minimally disturbed, sothat post-treatment is not necessary. The coordinated operationalsequence does not allow the side walls of the laying channel tocollapse, so that the soil is also prevented from caving in afterwards.If the blown-fibre method is used for introducing the opticalwaveguides, one or more hollow tubes are laid, as a result of whichpressurized water may then be channelled directly onto the cuttingwheel. This loosens the rocks or the subsoil.

FIG. 4 illustrates the system for the forcing-in process, by means ofwhich a minicable 1 is forced into a disused supply line 31. It isindicated that the minicable 1 which is to be forced in may, forexample, also come up against accumulation of dirt 32 which constitutesblockage of the supply line. Corresponding pressure has to be used topass through this accumulation of dirt 32. This figure furtherillustrates that the disused supply line 31 may have a plurality ofbranchings, so that it would also be possible for minicables to beintroduced from there. Valve openings 33 which are originally used forthe supply line and are each provided with a covering could be utilizedfor sleeve inserts for the newly introduced minicable system. At thestart of the injection location, the minicable 1 is likewise introducedvia a so-called laying bow 26 and a laying thimble 27, advancement beingeffected, for example, once again by means of advancement rollers 25.Here too, the minicable 1 is drawn off from a laying reel 24. It is alsopossible here for pressurized water to be injected, via a centralconnection 28 for pressurized water, to the end location of theintroduced minicable 1.

FIG. 5 illustrates the introduction of a minicable 1 into an existingsupply line, for example into a water pipe. At a bend 36 of the supplyline 35, the minicable 1 is introduced via an outlet location 37, theinlet location being provided with a corresponding seal 38. Theminicable 1 is advanced within the supply line with relative ease sincethere are no expected obstructions. Gas or flowing water injected intothe supply line assist the advancement of the minicable.

FIG. 6 illustrates the jetting process for a minitube, which is thenprovided with optical waveguides in the second process step by theblown-fibre principle and thus forms the finished minicable. As hasalready been indicated, first of all only the empty minitube is jettedinto the earth 17. In this case, pressurized water is channelled intothe minitube via the central connection 28, this resulting in theformation, at the end of the drilling head 40, of a pressurized jettingcone 39 by means of which the earth 17 is jetted out. The drilling tip40 is, in addition, made to rotate 41 in order to increase thejetting-out action. The minitube is also expediently made to rotate 42at the inlet location. After the minitube has been laid, the opticalwaveguides are then jetted or blown in by the blown-fibre process. Theinner wall of the tube is coated with plastic in order to improve thesliding movement of the fibre element during the blowing-in operation.

FIG. 7 illustrates the laying of a microcable in an asphalted roadsurface. As a supplement to laying the minicable 1 in a cut layingchannel 19, the laying channel 19 is first of all partially filled witha curable filling foam 43 after the minicable 1 has been laid. Finally,above this filling foam, the laying channel 19 is filled with awater-tight closure 44, for example consisting of hot bitumen, with theresult that the roadway surface is sealed off again. It can further beseen from FIG. 7 that a road structure is made up of various layers. Ananti-frost layer 48, generally comprising crushed stones, has a basecourse 47 arranged on it. The latter is adjoined to the top by a bindercourse 46, which, finally, is sealed by a surface course 45. It can begathered from this that the laying channel 19 must not cut right throughthe base course 47, in order that the supporting function is notimpaired.

FIG. 8 illustrates the position of the laying channel 19 by a roadcross-section with the abovedescribed layer structure comprising ananti-frost layer 48, an asphalt base course 47, a binder course 46 and asurface course 45. It is only the surface course 45 and the bindercourse 46 which are cut through by the laying channel 19, the asphaltbase course 47 only being cut to a partial extent. Depending on thenature of the road surface, the cutting depth is between 4 cm and 15 cm.A laying depth of approximately 7 cm is optimum.

FIG. 9 illustrates the same structure as in FIG. 8, but it is also shownhow the laying channel 19 is filled again and closed off after thetubular minicable has been laid. It can thus be seen that the base ofthe channel is provided, around the minicable 1, with a curable fillingfoam, over which a bitumen sealing compound or a preformed bitumen jointfiller is introduced in a sealed manner. It would also be possible forthe filling material 49 to be applied to the microcable, as the cablesheath, at the factory. It would form an additional protection forlaying the microcable. Suitable means or processes e.g. with the supplyof heat, could make the filling means expand. The laying channel 19 isconsequently sealed off, so that it is not possible for any surfacewater to penetrate. Optical waveguides 50 are indicated in the interiorof the minicable 1. In order to rule out damage during laying andcorrosion to the outer sheath of the metallic tube by leakage currentsin the ground, the minicable 1 is provided on the outer side with anon-conductive protective layer 51 which insulates the metal withrespect to the earth. A thin cable sheath of plastic can be applied asthe protective layer. For this purpose, a firmly adhering wear-resistantcoating may also be applied. The channel is sealed off with hot bitumen.If a preformed bitumen joint filler is used to seal the laying channel19, then it is introduced into the laying channel 19 on edge and thesurface courses to be connected are heated with a gas flame or infrareduntil a liquid bitumen film is obtained. A slight excess of thepreformed bitumen filler is subsequently rolled into the joint and thuscloses off the channel in a water-tight manner.

FIG. 10 illustrates how the laid minicable 1 is fixed by U-shapedholding-down devices 52. These U-shaped clamps 52 are pressed into thecut laying channel 19 from above. In this case, the web 54 of the clamp52 holds down the laid microcable or minicable. Tolerances in thechannel width are compensated for by the spring action of the lateralflanges. The flange ends may be provided with lateral claws 53 so thatthey can engage in the side walls of the laying channel 19. If thefilling compound softens, for example, due to hot temperatures, thecable holding-down devices 52 hold the microcable or minicable inposition without allowing it to rise up.

FIG. 11 shows a further exemplary embodiment for cable holding-downdevices 57. These comprise rivet-like metal bolts which are driven intothe cut laying channel 19 by means of their resilient shank 57. Thelens-shaped head 55 terminates at the roadway surface or is slightlyelevated. The cable route is easy to recognize by the heads 55 of theholding-down devices. The shank of the cable holding-down device 57 isprovided with barbs 56.

FIG. 12 illustrates a bending device for cable branchings and equalizingloops for thin-walled tubular microcables or minicables. In the case ofvery small wall thicknesses, the microcable or minicable is verysensitive to buckling. However, radii down to 30 mm can be producedwithout buckling by a bending device 61. For this purpose, themicrocable 1 is fixed with clamping tongues 62 and drawn around abending mandrel 60. For simple manipulation, a pressure-exerting roller59 can draw the microcable or minicable 1 around the bending mandrel,the hand lever 58 being actuated in the arrow direction. The pivot point63 of the hand lever is located in the axis of the bending mandrel 60.

FIG. 13 illustrates an exemplary embodiment for a marking of themicrocable or minicable route. Such a marking is particularly importantfor locating a microcable or minicable and serves, at the same time, asa warning marking for road construction work. The cut laying channel 19is hermetically sealed with a hot bitumen 65. In this case, the hotbitumen 65 has glass splinters 64, for example, added to it as filler,with the result that, when light shines thereon, the course of thelaying channel 19 is shown up by the reflection of light. Hot bitumenusually has a very low viscosity for processing. For a laying-channelwidth of from 7 to 10 mm, the viscosity of the hot bitumen can beincreased by aggregates. The mechanical properties of the sealingcompound may then also be compared with those of the existing roadsurface. For the marking, use may be made of ground, coloured glasssplinters as fillers and aggregates. Different colouring and reflectionmean that the cable route may then be recognized clearly. Under normalwear of the roadway surface, a number of glass particles are alwaysexposed and are thus easy to recognize.

FIG. 14 illustrates that the microcable or minicable may be providedwith equalizing loops 66 for length equalization and also for cablelead-throughs at a sleeve. This means that excess lengths are taken upduring laying and crimping of the tubes and that subsidence in theearth, in the road and expansions in length in the microcable orminicable and the road surface are compensated for without detrimentallongitudinal stressing. Such equalizing loops 66 are to be fitted duringlaying, in which case the laying channel 19 has to be provided at theappropriate locations with a corresponding depression 67 or widening inorder to obtain sufficient space for the equalizing loop 66. Suchequalizing loops 66 are preferably to be fitted in front of sleeves,cable branches and bends. If a microcable or minicable is to be laid atright angles, then a core hole has to be introduced vertically into theupper road structure. In this case, the diameter depends on the minimummicrocable or minicable radius which can be bent without buckling bymeans of the abovedescribed bending device. The core hole shouldsubsequently be sealed again in a frost-resistant manner by asphalt.U-shaped bends of the minicable are also possible instead of theequalizing loops.

FIG. 15 illustrates an arrangement for a sleeve 68 into whichmicrocables and minicables 1 are fed via cable inlets 70. Theappropriate measures such as connecting or splicing are then carried outin the interior of the cable sleeve. Such a cable sleeve preferablycomprises a round steel cylinder and is introduced into a core hole ofthe ground 17. A sleeve cover 69 which can be placed in position fromabove closes off the sleeve interior. After the sleeve 68 has beenintroduced and the microcable 1 has been introduced in the sleeve, theupright core hole, which can lead into the substructure of the road, isconcreted into the roadway in the lower region. The sleeve is thus nolonger subject to settling. Sealing with respect to the upper roadstructure 72 is effected with asphalt or liquid hot bitumen. Sealing inthe cable inlets 70 takes place, for example, with conventional cuttingring seals or other seals which are known per se for cable sleeves. Thincopper tubes into which the cable ends can be introduced have alsoproved expedient. These are crimped onto the outer wall of themicrocable by radial pressing. These crimped connections are resistantto tension and pressurized water. At the top, the core hole isterminated by a load-bearing cover 73 level with the road surface 72. Ifnecessary, it is also possible for the cover to be located beneath theroadway surface. The optical waveguides may be arranged, in a mannerknown per se, with excess lengths and splices in the interior of thecable sleeve 68. The round embodiment of the cable sleeve 68 means thatit is expedient to introduce the optical-waveguides helically, with theresult that they can easily be moved upwards if required.

It is also advantageous to use a small shaft instead of the sleeve 68,this small shaft, in turn, receiving a sleeve.

Discharge means and feed means may likewise be run, as minicables ormicrocables, in a manner of an overhead cable or non-supported cable.

The object of one development of the invention is to find a process withthe aid of which it is possible to cut laying channels for minicables ormicrocables in the solid ground in one operation. The set object isachieved, in accordance with the process explained in the introduction,in that a laying channel is cut by means of a laying unit whosecutting-wheel arrangement is varied in terms of thickness such that thewidth of the laying channel is adapted in one cutting operation to thecorresponding diameter of the microcable or minicable used.

Advantages of the process according to the development of the inventionmay particularly be seen in that it is now possible to produce layingchannels in solid surfaces such as asphalt and concrete, road surfaces,curbstones or stone slabs by means of a laying unit in which the cuttingwidth can be set to the respective diameter of the minicable ormicrocable used. For this purpose, for example a cutting-wheelarrangement comprising two standard blades with the interposition of aspacer ring is drawn onto the axle of the laying unit. Exchanging thespacer ring means that the cutting width can thus be changed.

In the case of wide laying channels, a central web first of all remainsin the ground, but the invention provides measures by which theresulting central web is broken out at its base during the cuttingoperation. This is effected by appropriate configuration of thecircumferential surface of the spacer ring, e.g. by introducing groovesof a suitable shape, for example of a rectangular or sawtooth shape, orby providing bar-like, flexible brushes on the circumference. These alsoclean the channel of abrasion dust. This results, in particular, in theadvantages outlined below:

-   -   Production of rectangular laying channels of any width.    -   The width of the laying channel can be determined by exchanging        the spacer ring.    -   The double cut in one operation means that the wear on tools is        uniform, the blades not being subjected to bending stress, so        that unbalances do not occur.    -   The initially produced central web in the laying channel is        broken out at the base during the cutting operation.    -   Appropriate configuration of the outer circumference of the        spacer rings means that the laying channel is also cleaned at        the same time.

FIG. 16 shows a rectangular laying channel VN in a solid ground surfaceSO, a double arrow indicating that the channel width VB has to bevariable in accordance with the minicable or microcable type MK used inorder to be able to achieve the necessary width in a single cuttingoperation.

FIG. 17 illustrates the production of the widened laying channel by twoblades which are spaced apart from one another in accordance with therespectively introduced spacer ring, with the result that a central webMS first of all remains between the two partial channels TN1 and TN2.However, appropriate circumferential configuration of the spacer ringmeans that this central web MS is immediately broken off at the base BSduring the cutting operation, this resulting in the wide laying channelshown in FIG. 16.

FIG. 18 illustrates a cross-section of the cutting-wheel arrangement,which comprises two blades TS1 and TS2 with a spacer ring DR locatedtherebetween, the width of the spacer ring DR being selected such thatthe ring, together with the two blades TS1 and TS2, provides thenecessary width for the laying channel VN. The drive axle AS isintroduced in the laying unit VE via corresponding linkages G.

FIGS. 19 to 22 illustrate the configuration of the circumference of thespacer ring DR, the blade TS2 having been removed for this illustration.The blade TS1 is provided with appropriate cutting teeth in theconventional manner. These cutting teeth Z may also be provided withhard metal. If appropriate, the cutters may be exchanged. Preferably,the cutters should be made to protrude alternately beyond the cuttingblade TS3 from the blade centre, as can be seen from FIG. 22. Thisscrewing action allows the blade TS3 to cut a clearance at the channelflanks FL. “Seizing” is avoided. The spacer ring DR is provided on itscircumference with grooves or cutouts of widely varying configurationwhich break off the central web and clean the laying channel. An airpressure by which the laying channel is freed of fragments is producedby way of the cutouts or grooves. This simultaneously achievesself-cleaning of the laying channel as it is produced.

FIG. 19 illustrates rectangular cutouts RA, and FIG. 20 illustratessawtooth-shaped cutouts SA, on the outer circumference of the spacerring DR. In FIG. 21, this operation is carried out with the aid ofbar-like, flexible brushes B by way of which the central web is brokenand the fragments are removed from the laying channel VN.

FIG. 22 illustrates the lateral offset or staggering of the hard-metalteeth Z, which make it possible for a blade TS3 to run freely. Thisarrangement applies for each of the blades.

It is also possible to use such cutouts RA to cut out a material whichhas the properties of bitumen.

The object of a further development of the invention is to find aprocess by which the laid minicable or microcable can be removed againfrom the laying channel, in which case the filling material has to beremoved beforehand. The set object is achieved according to theinvention, in accordance with a process of the type mentioned in theintroduction, in that a tension-resistant release element for liftingthe laid minicable or microcable is introduced, when said cable is laidin the laying channel, above the minicable or microcable in the fillingmaterial of the laying channel, in that the tension-resistant releaseelement is then drawn out during the lifting operation, in which casethe laying channel is also released of filling material, and in that theminicable or microcable is then removed from the laying channel.

The problem with lifting the minicable or microcable (only the termmicrocable will be used from now on) is that the cable runs in a layingchannel which is covered in a sealed and well-adhering manner with afilling material above the microcable. In this case, use is made of afilling material which has viscous and adhering properties, for examplebitumen. Accordingly, the microcable cannot be drawn out before not thefilling material is removed. Likewise, further, secondary cutting of thelaying channel is not an option since the filling material would onlysmear on account of its viscous consistency. The invention solves thisproblem, then, in that a tension-resistant release element is embeddedabove the microcable, which release element can be drawn out or pulledout if required and also removes the filling means in this operation. Itis advantageous here if, from the outset, the microcable is not wettedwith the filling means, so that, as far as possible, there is noadherence between the two. The tension-resistant release element may bedesigned as a separate element, for example in the form of a line, of aprofile body or of a strip. Such release means may consist, for example,of plastic or of metal, for example of steel. However, it is alsopossible for special release means or plastic materials to be appliedaround the microcable, for example a plastic film of polyethylene, sothat adherence between the microcable and the filling means occurs onlynegligibly, if at all. Furthermore, it is possible for this purpose thatthe laying channel be filled above the microcable with a release meanswhich is designed as a filling profile and is pressed into the layingchannel, if appropriate with additional sealing with respect to theborders of the laying channel. Once again, a viscous material such asbitumen is particularly suitable for this purpose. Particularly elasticmaterials, for example rubber or elastic plastics, are suitable for sucha filling profile.

However, the tension-resistant release element may also form aconstituent part of the sheathing of the microcable, it being possiblefor the sheathing material to be separated easily from the microcable,so that, once again, the filling material is first of all removed withthe tension-resistant release element during the lifting operation.

If the tension-resistant release element consists of electricallyconductive material, it may also be used, in addition, for the powersupply along the microcable.

It is illustrated in FIG. 23 that a microcable MK is introduced in thecut laying channel VN of the solid ground VG and, according to theinvention, a tension-resistant release element ZT in the form of a metalor plastic line has been arranged above said microcable during thelaying of the same. Above this, the laying channel VN is filled in asealed manner with a filling material FM, for example consisting ofbitumen. Before the microcable MK is lifted, the tension-resistantrelease element ZT is, then, drawn out in order also to remove thefilling means FM from the laying channel VN, this resulting in thelaying channel VN then being free and it being possible to lift themicrocable MK without risk.

FIG. 24 shows that it is also possible for the laying channel VN to befilled with a tension-resistant filling profile FP, which is drawn outif required. This tension-resistant filling profile FP may additionallybe introduced with a sealant, for example with bitumen, this resultingin the laying channel VN being sealed reliably.

The object of a further development of the invention is to provide aprocess for the power supply of a minicable or microcable with opticalwaveguides. The set object is achieved, by a process of the typementioned in the introduction, in that the metallic tubes of themicrocables or minicables are connected to the central power supply.

In general, at the present time, the power is supplied by an additionalpower cable which is supplied from a central point. The disadvantage isthat a separate power cable has to be laid over a large distance. Costsfor an additional cable route and voltage losses have to be accepted.Additional measures for the power supply likewise have to be taken forthe optical-waveguide submarine cable known per se.

However, a minicable or microcable of the type described comprises atubular metal sheath. This protects the optical waveguides againstdamage during laying, guarantees a certain excess length of the fibresand is stable with respect to transverse forces. Moreover, the solidground in which the laying channel is provided gives the minicable ormicrocable the necessary protection against external mechanicalinfluences. The electric properties of this minicable or microcable,however, are not utilized. If, then, the metal tubes of these minicablesor microcables are electrically interconnected at the connectinglocations, as is effected, for example, with the aid of metallicconnecting sleeves, this system can be used for a power supply. A secondconductor may provide the return conductor or, if it is insulated, thepower supply. With the return conductor, insulation may be dispensedwith if required. The return conductor may additionally assumeprotective functions.

Such a minicable or microcable and the power supply may also be producedas a continuous cable. A separate return conductor can be dispensed withif two insulated microcables are laid. Use may also be made of twomicrocable tubes in one microcable with corresponding common insulation.The cable sheath insulates the tubes with respect to one another and tothe earth. Such a minicable or microcable can easily be bent around anarrow axis and laid.

With such a power supply, the strength and the conductivity are realizedby way of the cross-section of the cable sheath or of the metallic tube.Sufficient electrical interconnection is guaranteed by crimping metallicsealing heads of a cable sleeve to the metallic tube of a minicable ormicrocable. For the return conductor of the power supply, use may alsobe made, for example, of cable holding-down devices, if these consist ofmetal. The task of these cable holding-down devices is, in the originalsense, to position the cable securely at the correct laying height inthe laying channel. When direct current is used, it is also possible todispense with a return conductor if earthing takes place. If themetallic tubes of the minicables or microcables are provided with aninsulation layer, then, in addition to the possibility of insulatedpower supply, the following advantages can also be achieved:

-   -   corrosion protection for the metal    -   the metal tube is protected against mechanical damage during        laying    -   the insulation layer forms a wear layer for the drawing-in        operation of the microcable    -   the insulation layer forms heat insulation when sealing the        laying channel with hot bitumen    -   the insulation layer forms vibration insulation in the case of        heavy traffic.

FIG. 25 shows the through-connection of the power supply with the aid ofa metallically conductive cable sleeve KM. The power is supplied throughthe microcables MK1 and MK2, the ends of which are electricallyinterconnected by the sleeve tube MR. The electric contacting, therelief of tension and the sealing of the microcables MK1 and MK2 takeplace at the crimp locations of the sealing heads DK. In this case, theouter side of the cable sleeve KM is additionally provided with anelectric insulation IS.

FIG. 26 illustrates in the position of a microcable MK which [lacuna] inthe laying channel VN above a power cable SK provided with an insulationSKI.

This power cable SK is a single-phase power cable and the tube MKR ofthe microcable MK is provided with a plastic insulation IS. After theintroduction of the cables, the laying channel VN in the ground VG isfilled with a sealing compound VM. The power is thus supplied via theinsulated microcable MK and the insulated power cable SK.

FIG. 27 shows the arrangement of a non-insulated microcable NK with itsmetallic tube MKR, in which the optical waveguides are arranged, abovean insulated power cable SK, within a laying channel VN. Thesingle-phase power-supply cable SK is, once again, insulated and thenon-insulated tube MKR of the microcable MK is earthed. In this case, aninsulation can be dispensed with.

FIG. 28 shows the power supply through a microcable MK whose tube MKR isprovided with an insulation IS. Above this, an earth strip, as returnconductor RL, ensures the return conduction. In this case, the returnconductor RL serves simultaneously as additional protection for themicrocable MK.

FIG. 29 shows the laying of a microcable provided with insulation IS, inwhich case a continuous cable holding-down device NH secures theintroduced cable MK in its vertical position. The cable holding-downdevice NH has obliquely positioned side walls NHS which are supportedagainst the wall of the laying channel VN. In this case, returnconduction of the power supply takes place via the cable holding-downdevice NH, which serves moreover as an upward protection and guard.

FIG. 30 illustrates the power supply through a microcable MK which isarranged, with an additional wire ZS, with an insulation IS. Saidadditional wire ZS is electrically insulated with respect to themicrocable MK. Moreover, the material of the additional wire isdetermined such that it can be used as a supporting wire with thenecessary nominal tensile force. It consists, for example, of steel orbronze.

FIG. 31 shows the power supply, once again, via a microcable MK. Anadditional wire ZS is integrally moulded on the microcable MK via aninsulation IS, the connection between the two taking place via a web ST.The microcable MK may be separated from the additional wire ZS in theregion of the web ST if required. Such a separation is practical, forexample, for bridging connecting sleeves.

FIG. 32 shows the arrangement of two microcables MK1 and MK2 located oneabove the other in the laying channel VN. The two microcables MK1 andMK2 are insulated separately and can be laid separately from one anotheror together. Each microcable may expediently be spliced to a singlesleeve and electrically interconnected.

FIG. 33 shows the power supply through two microcables MK1 and MK2 whichare located one above the other and are insulated separately, but areconnected to one another via a web ST. For splicing, the microcables MK1and MK2 can be separated from one another in the region of the web ST,with the result that each microcable MK1 or MK2 can be spliced indifferent single sleeves and electrically interconnected.

The object of a further development of the invention is to find aprocess with the aid of which a laid minicable or microcable can belocated. The set object is, then, achieved, in accordance with processof the type mentioned in the introduction, in that the route of theoptical minicable or microcable laid in a laying channel is followedwith the aid of a detector.

Advantages of the invention over the prior art can be seen, inparticular, in that, with the aid of a detector, the laid minicable ormicrocable can be traced so accurately that, for example, it can even beentered, with relatively low tolerances, for archiving in town streetplans and cable-route plans. The process using a detector according tothe invention can also be used to locate the cable in the ground forrepair purposes, it being possible for interruptions in the cable to belocalized accurately. It is just as important, before the laying channelis cut, to check the route as to whether or not there are already supplylines in the ground. Such a process, which is based on the operation ofsuitable detectors, can thus be used for the acceptance and approval ofa new cable route, since the quality of laying and the laying depth canbe established at any time.

It is thus expedient to arrange such a detector, as a functional unitfor locating cables, in front of a joint-cutting machine, so that anymetallic object, for example a cable or supply line, which is located inthe ground, is detected in each case. For laying minicables ormicrocables, detection can take place via the metal tube itself, via areturn conductor which is carried along or else via cable holding-downdevices in the laying channel. These cable holding-down devices may alsobe used, for example, for the power supply and for a protective functionfor locating the minicable or microcable. It would be possible forholding-down devices to have a fixedly predetermined code or else to befreely programmable. A service vehicle which is used to trace the laidcable is expediently made available for this process. This unit producesthe reference for a marking points, and stores the route in which theoptical cable is laid, so that the route can be transferred ontoexisting street plans. In this way, both the position and the depth ofthe laid microcable can be established.

FIG. 34 describes the principle of the process for locating an opticalcable, in particular a minicable or microcable, with the aid of adetector D which is accommodated in a service vehicle. When this vehicledrives over a laying channel VN, it is established by way of the emittedand reflected locating signal OS that a laying channel VN has beendriven over. In this exemplary embodiment, the microcable MK has beenlaid in the laying channel VN, and the laying channel VN has then beenfilled with filling material, for example bitumen, metallic fillershaving been added to the filling material.

FIG. 35 shows a longitudinal section through a laying channel VN insolid ground VG. The microcable MK is introduced at the base of thelaying channel and is held in position with the aid of cableholding-down devices NH, which are of a dowel-like design. Theindividual cable holding-down devices NE are provided with magnets whosemagnetic fields can be located by the detector passing over them. Thealignment of these magnets may be the same or else alternately differentin all of the cable holding-down devices NE. Alternate alignment of themagnets M with the poles MN and MS can produce a system of alternatemagnetic fields by means of which it is even possible to establish acoding for the laid minicable or microcable. The laid cables can beidentified accurately in this manner, with the result that it ispossible to rule out mix-ups during repair work.

FIG. 36 illustrates a laid microcable MK, in the laying channel VN,which is held in position by magnetic cable holding-down devices NHN.Here too, poles of the magnetic cable holding-down devices NHM may beclamped in the laying channel VN with alternate orientation of themagnet poles NEMN and NHMS, so that coding of the cable route ispossible in this case as well. The U-shaped cable holding-down devicesNHN wedge in during laying and are supported on the channel wall. TheU-shaped cable holding-down devices are magnetically insulated withrespect to one another and are pressed in individually by thecable-laying machine. These magnetic cable holding-down devices NHM maybe permanently magnetic or magnetized individually during laying. Heretoo, the magnetic field can be detected through the filling material,which is not illustrated in this case.

FIG. 37 illustrates, once again, a microcable MK laid in a layingchannel VN, this microcable being held in position by bar-like cableholding-down devices SNHM. These bar-like cable holding-down devicesSNEM likewise wedge in during laying and are supported against thechannel wall. Once again, the bar-like cable holding-down devices SNEMare magnetically insulated with respect to one another, and may bepermanently magnetic or only magnetized individually during laying. Heretoo, it is possible to allocate an individual coding (morse) to eachlaid optical cable by alternating the magnet poles. It is also possiblein this case, in the manner described, for the magnetic field to bedetected by a detector in accordance with the process according to theinvention.

A grid-like cable holding-down device GNE is illustrated in FIG. 38.Here, the bar-like, magnetic cable holding-down devices SN, HM arefastened on two longitudinally running support filaments TF, theindividual bar-like, magnetic cable holding-down devices SNHM beingmagnetically insulated from one another. During the laying operation,this grid-like cable holding-down device GNH can be easily unwound andintroduced above the cable in a clamping manner. Such a structure canalso be used in a simple manner to measure the length of the cable routesince a kind of graduated scale is provided by the uniform spacing ofthe bar-like cable holding-down devices SNHM. The individual bar-likecable holding-down devices SNHM may be permanently magnetic or onlymagnetized individually during laying. Here too, it is possible toprovide a coding by alternating the magnet poles.

FIG. 39 illustrates that the cable holding-down devices KNHM can be, asit were, tacked or clamped onto the support filaments TF. This may alsotake place on site, in which case any desired coding pattern can beproduced. Such a coding may also take place, for example, by varying thespacing between the individual bar-like, magnetic cable holding-downdevices KNHM.

It is illustrated in FIG. 40 that the cable holding-down devices ENHMmay also have their ends E fitted onto a support sheet TFOL. Here too,it is possible to vary the polarity and the spacing of the individualbar-like cable holding-down devices ENHM for a corresponding coding.During filling of the laying channel with hot bitumen, the sheet thenmelts, with the result that the hot bitumen can fill the laying channelbetween the bar-like magnets ENHM. The bar-like cable holding-downdevices ENHM remain wedged in the laying channel and hold the microcablein the corresponding position.

In addition to the abovedescribed possibility of purely passive codingby cable holding-down devices NH, an active coding provided byelectronic components is illustrated in FIG. 41. FIG. 41 is derived fromFIG. 35. However, the magnets have been replaced by electronic pulsegenerators I. The information of the pulse generators I can beinterrogated from the road surface by a movable induction loop IS.

The pulse generators I can emit cable-specific information, e.g.operator name, route to which the relevant cable belongs, laying depth,laying date, number of optical waveguides, etc.

A freely programmable chip C which is assigned to the microcable MK orto the holding-down device NH is illustrated in FIG. 42.

It can store and reproduce information (cable, sleeve, operator, freeoptical waveguides, etc.). Interrogation can take place inductively viathe support filaments (TF) or by electrically contacting the cablesheath or the carrier filaments from the sleeve.

In FIG. 43, the programmable chip CH is accommodated in the sleeve M, sothat information can be emitted from the sleeve. It is also possible forfurther electronic active components to be accommodated here. The powersupply can take place from here, it also being possible for the supportsurfaces TF of the cable holding-down devices NE to be designed, forexample, as power-supply conductors.

The abovementioned optical cables are referred to as microcables and arepreferably laid in laying channels in solid ground. On account of theirsmall diameters, the laying channels can be kept very narrow, so thatthey can be produced with the aid of cutting processes. Particularlysuitable laying surfaces are substructures and roads consisting ofasphalt or concrete. The laying depth is very small and is between 7.5and 15 cm. Such optical-waveguide cable systems are particularlywellsuited for laying in surfaces which have already been establishedfor this purpose, since high-outlay excavation work does not have to becarried out. Moreover, the laying time is very short, which isparticularly advantageous in the case of roads. After the introductionof the microcables into the cut laying channels, these are filled withsuitable filling material, for example with bitumen. Further examples ofsuitable laying channels are expansion joints which are provided betweenindividual concrete slabs or are provided as a precautionary measure inconcrete slabs for road surfaces. Microcables may likewise be laid inthese expansion joints. These expansion joints are likewise filled withfilling material, so that the microcables are protected.

However, it must also be possible for such microcables to be lifted, forexample when repair work has to be carried out on the tube. Thesemicrocables cannot, however, be removed from the laying channel togetherwith the filling material since the forces required for this purposewould damage the microcable further. Moreover, the tube has to berestored in the region where damage has been established and thenintroduced into the laying channel again.

A further object of the invention is to develop a process by which it ispossible to remove a microcable of the abovedescribed type from thelaying channel and to repair the same. The set object is, then,achieved, with the aid of a process of the type mentioned in theintroduction, in that, with the aid of a unit for exposing themicrocable, the filling material is removed from the laying channel overa length which is required for the introduction of a repair set, saidrepair set being formed from two cable sleeves, two equalizing loops anda connecting tube between the cable sleeves, in that the microcable islifted from the laying channel freed of the filling material, in thatthe tube of the microcable is shortened over a length which correspondsto the repair set and in that the repair set is connected tightly to thetwo ends of the microcable.

Microcables of the abovedescribed type are laid in the upper region ofroads and footpaths. In terms of dimensions, they are very small andcould thus easily be overlooked when earth work is carried out, so thatthe possibility of damage is considerably higher than in the case ofconventionally laid communication cables. It is thus necessary to have aquick process for repairing a damaged microcable, by means of which thedamage can be rectified in a relatively simple manner and in a shortperiod of time. A repair set is designed for this purpose, which set ismade up of existing standard parts, that is to say of two cable sleeveswith a connecting tube located therebetween, this connecting tubebridging over the length of the damaged area, and of two connectionunits which are connected to the ends of the damaged microcable. Thedamage location, for example a cut-through tube of the microcable, maybe located, for example with the aid of an electric test signal, byradiation. However, if the tube is still connected metallically, thedefect location in the optical waveguide has to be traced and localized,for example with the aid of an Optical Time Division Reflectometer(OTDR). In this case, some of the introduced light is reflected back byway of defect locations in the glass (soiling, splice, etc.). If thetransit time is measured, the spacing between the defect location andthe transmitter can be measured.

For the repair, the microcable has to be exposed, on either side of thedefect location, to such an extent that there is sufficient excesslength for manipulation and for splicing in the cable sleeves. For thispurpose, however, first of all the laying channel has to be freed offilling material since it is not otherwise possible for the microcableto be lifted without further damage. The laying channel is exposed bycutting out or scraping out—possibly in a number of layers—or by heatingthe sealing compound, by cutting out and removing with the aid of acutter guided in the laying channel, or by heating the microcable orfurther electrically heat-conductive parts which may be located in thechannel close up beside the microcable.

In each of the two cable sleeves, which are suitable for receivingmicrocables at least in the inlet region, in each case one end of thedefective microcable is introduced and is spliced there to opticalwaveguides, which are guided to the second cable sleeve via theconnecting tube. These optical waveguides are then spliced, in thesecond sleeve, to the optical waveguides of the second end of thedefective microcable. The cable sleeves are expediently sunk in coreholes which are cut in tangentially beside the exposed laying channel.The inlets of the cylindrical cable sleeves are arranged tangentially onthe sleeve cylinder, with the result that the inlets of the microcableconnections in the form of equalizing loops only have to be deflected toa slight extent. The microcable connections likewise comprise tubes andare designed as equalizing loops, so that it is possible to compensatefor tolerances and longitudinal expansion when the sleeves areintroduced and during operation. The tight connections to themicrocables are produced by crimping the ends of the equalizing loopsonto the ends of the microcable. After these operations, the layingchannel can be filled with filling material again.

A break KB in a microcable NK is illustrated in FIG. 44, the fillingcompound having already been removed from the laying channel over alength which is necessary for the repair. All that is left in theexposed laying channel FVN, which is provided, for example, in a solidroad surface VG, is a small layer of filling compound above themicrocable NK, which layer of filling compound, for safety reasons, isnot removed in its entirety, so that the microcable MK is not damagedmechanically by the tool. An appropriate control means as is furtherexplained at a later point in the text is suitable for this purpose. Thelaying channel with the virtually exposed microcable MK is thenaccessible from the road surface SO, so that the two ends of themicrocable MK which is to be repaired can then be removed simply andcarefully.

FIG. 45 illustrates the already outlined process for repairing amicrocable MK which is broken at the location KB, the exposed layingchannel FVN being viewed from above in this case. It can be seen thattwo core holes B have been drilled vertically into the ground, virtuallytangentially beside the exposed laying channel FVN, at a spacing whichis required for the excess lengths of the optical waveguides, and acylindrical cable sleeve KM has been introduced into each of the coreholes. These cable sleeves KM are designed for receiving microcables andhave tangentially running cable-sleeve inlets KE to which tubularequalizing loops AS are connected. The diameter of these tubularequalizing loops AS is adapted to the diameter of the microcable MK, thetight connections usually taking place by crimping AR. The equalizingloops AS serve for equalizing tolerances and expansions. Since the cablesleeves KM have tangential cable inlets KE, the equalizing loops AS canbe fitted on with only small bends, so that they can be run into theexposed laying channel FVN without buckling or stressing.

FIG. 46 shows the arrangement in accordance with the outlined repairprocess and constitutes a longitudinal section of the arrangementaccording to FIG. 45, for the sake of simplicity the cable sleeves beingillustrated in a sectional and simplified form in order better to showthe conditions. It can thus be seen that the equalizing loops AS areconnected by means of crimping AK, on the one hand, to the tube ends ofthe microcable MK which is to be repaired and, on the other hand, to thecable inlets KE of the cable sleeves KM. The optical waveguides LWL ofthe microcable MK are each fed to the corresponding cable sleeve KM byway of the equalizing loops AS and, there, are spliced, at splicingunits SK, to optical waveguides LWL which lead, via the connecting tubeVR, to the respectively second cable sleeve KM. All the connections canbe restored in this manner. After the cable sleeves KM have been closedoff, the previously exposed laying channel FVN can be filled withfilling material again.

FIG. 47 shows a unit GF for removing the filling compound FM from thelaying channel VN provided in solid ground VF. A microcable MK is laidat the base of said laying channel VN and has to be lifted, for example,due to a break in the tube. In this case, the microcable MK is providedwith an insulation layer IS. For the purpose of removing the fillingcompound FM, use is made, in this process, of a heated cutter SCH whichis mounted cardanically, that is to say rotatably, at a pivot point DPof the unit GF and thus compensates for inaccuracies in the guidance ofthe cutter. Also provided is a spring mechanism F which is designed suchthat the cutter SCH can tilt out upwards if the lifting-out forceexceeds an adjustable value. This cutter SCH is mounted on a mobile unitGF and is heated, for example, from a container for fuel BS via aconnecting line SH. A motor M ensures that the unit GF advances abovethe laying channel VN on the road surface. An electric measuring deviceMV is used, during the process, to monitor that the microcable is notadditionally damaged by the cutter SCH being introduced too deeply, thetube of the microcable NK and the metallic cutter SCH being connected toa continuity tester. If, then, the insulation layer IS is damaged by thecutter SCH, the measuring device MV responds and the depth of engagementof the cutter SCH may then be corrected. It is also possible for theexposing operation to take place in layers.

Further aids may also be provided in order to expose the microcable inthe laying channel. Thus, for example, the insulation of the microcablemay be designed as a type of zip fastener, so that the tube itself doesnot come into contact with sealing material when the latter is beingintroduced. After the filling material has been removed and the “zipfastener” has been opened, the microcable can be completely freelyremoved from the insulation. Furthermore, it is also possible for aripping wire to be introduced into the laying channel above themicrocable, it being possible for this ripping wire to be used forpulling out the filling material. If continuous cable holding-downdevices have been introduced above the microcable during the layingoperation, these cable holding-down devices may also be used forremoving the filling material.

If the microcable has an insulation, this insulation is extremelysuitable as a release means between the metallic tube of the microcableand the well-adhering filling material (for example bitumen) which sealsthe laying channel. A cable sheath consisting of polyethylene, paper ora swelling nonwoven acts as a zip fastener as the microcable is exposed,since those materials do not adhere to the tube but adhere well to thebitumen. Such a cable sheath thus acts as a release means between themetal tube and the filling material. The metal tube of the microcableshould have a smooth surface in order to reduce the adherence. Thelaying channel is exposed in the abovedescribed manner, but theinsulation remains in the laying channel.

It is also possible to lay a strand of foam rubber GU as release meansbetween the microcable MK and the filling material FM, as is shown inFIG. 48. In such an arrangement, the cutter of the laying unit wouldthen not have to be heated. It is also possible to use a particularlystrong cable sheath. In addition, the cable sheath may also bethickened.

In accordance with the same process, it would also be necessary toremove a filling material from a laying channel which are introducedbetween the individual slabs of a concrete roadway or in expansionjoints of slabs on which it is possible to drive it would therefore alsobe possible to dispense with the operation of introducing an additionalchannel with the aid of a cutting blade in the case of concrete roads ifthese channels in the concrete have a dimension which correspondsapproximately to the diameter of a microcable, such cables can beintroduced into these already existing channels without further measuresbeing taken. These channels are then likewise filled with fillingmaterial and sealed. Since such seals in the channels of the concreteslabs have to be renewed at certain time intervals for safety reasons,there is the opportunity to use such occasions to lay new microcableswithout additional cost, time-saving also playing a role here. Moreover,the road structure would not be weakened by additional laying channelsfor the microcable. It would be possible for the expansion joints to bemade deeper or wider by abrasive grinding.

Concrete roadways are divided up, directly after casting, by dummyjoints into individual slabs of a size of from 7.5 m to 20 m. Thesedummy joints are predetermined breaking points which are produced bycuts of a depth of approximately 5 to 10 cm and a width of approximately8-10 mm. Sealing strip, foam rubber or filling bitumen seal the dummyjoints against dirt and surface water. Such channels are likewisesuitable for the laying of microcables. In order to protect themicrocables laid therein and in order to be able to compensate forirregularities caused by the soil mechanics, it is expedient to widenthe dummy joint at each concrete-slab joint, so that the microcable hassufficient opportunities for compensation in these areas. For thispurpose, a core hole with a diameter of 8 to 10 cm would be sufficientin order to protect the laid microcable when roadway slabs are displacedwith respect to one another by subsidence, earthquakes or similar groundmovement. Shearing off or buckling of the laid microcable could thus belargely ruled out.

The length of the repair set depends on the damage location. In order tohave sufficient excess length of fibre, a fibre supply of approximately1.5 m has to be allowed for each sleeve. The connecting tube VR, andthus the length of the repair set, is always 3 m longer than the defectlocation which is to be bridged.

The filling material can also be heated, for example, by heatingcurrent-carrying conductors which have been introduced in the fillingmaterial. The cable holding-down devices, for example, can be used forthis purpose.

The object of a further development of the invention is to provide aprocess in which the microcable is fixed continuously along its lengthduring the laying operation.

The set object is, then, achieved, by a process of the type mentioned inthe introduction, in that the microcable is fixed in a laying channel inthe ground with the aid of a continuous profile body consisting ofelastic material, and in that the laying channel is sealed byintroducing a sealant.

The microcable, then, is fixed, in a simple manner and ideally followingthe laying of the microcable in the laying channel, by introducing acontinuous profile body at the base of the laying channel. Thecontinuous, elongate profile body preferably comprises an extruded,rubber-like plastic, which is usually referred to as foam rubber. Theaction of pressing this profile body into the laying channel deforms itelastically and, due to the elastic prestressing, wedges it against thewalls of the laying channel. In so doing, irregularities are compensatedfor by the elastic material. The material consists of a rot-proof softrubber which is resistant to temperature and UV. If required, thisprofile body may additionally be sealed at the top with a sealant, forexample with hot bitumen. In this way, the profile body is additionallyfixed mechanically in the channel. This gives the following advantagesover holding-down devices comprising metal clamps or similar elements:

-   -   Less hot bitumen is required for the sealing.    -   The profile body is laid quickly, in some circumstances        immediately after.    -   The laying operation can run continuously.    -   This alone provides rough sealing with respect to surface water.    -   The elastic material of the profile body can allow for        expansions in the ground.    -   There is only slight shrinkage of the hot bitumen in the sealing        area, so that there is hardly any “subsequent settling”.    -   The channel filling, comprising the profile body and the        sealant, can be easily removed again since a type of        zip-fastener function is set up.

The main purpose of the invention, however, is to fix the microcable inthe laying channel with the aid of a profile body. Furthermore, thechannel is sealed towards the road surface and the cable is protectedagainst mechanical loading and vibration.

In the simplest exemplary embodiment, use is made of an elastic profilebody with circular cross-section which is pressed in directly above themicrocable, for example using a roller or roll, the remaining free spacein the laying channel being sealed off towards the top with a hotbitumen. On account of its elastic properties, pressing in of theprofile body also fills the cavities between the microcable and thelaying walls.

An exemplary embodiment in which the microcable is already sheathed withan elastic profile body is also advantageous.

However, use may also be made of dimensionally stable, elasticallydeformable sealing profiles, which then have deformable formations, forexample barbs, which make it possible for said sealing profiles to clampand catch on the channel walls and irregularities in the laying channel.

As sealant for sealing the laying channel against the penetration ofwater, use is preferably made of heat-softenable materials, for examplefusible bitumen or hot bitumen or hot-melt adhesives known per se, e.g.consisting of polyamide. These sealants are introduced, under the actionof heat, after the microcable has been laid in the laying channel, saidlaying channel then being sealed after setting of the sealants.

Use may also be made of temperature-resistant and dimensionally stableprofile bodies in which there are arranged free ducts into whichmicrocables or else free optical waveguides are drawn. The opticalwaveguides are introduced, then, for example by cables, fibres or fibreelements being blown or drawn in, it being possible for these operationsto take place before or else after the introduction of the profile body.

It is thus possible for a microcable to be fixed in its laying channelin a simple manner by a continuous profile body, the cut laying channelsin the solid ground, for example a road, being closed off in awater-tight manner. The microcables can be laid better using suchprofile bodies and, in the event of a repair being necessary, theseprofile bodies can be easily removed again from the laying channel. Theprofile bodies which are introduced above the microcable simultaneouslyprotect against high temperatures (from 230 to 280° C.), which may occurwhen the hot bitumen or the hot-melt adhesive penetrates. Moreover, itis also possible for the profile bodies to compensate, to some extent,for changes in length in the case of irregularities in the road(subsidence) or in the case of different thermal expansions of cable androad surface.

However, the microcables may also be provided during manufacture with asheath consisting of soft, as far as possible cellular or expandedplastic, so that this sheath already assumes the function of the profilebodies. Such a microcable is then held down by the applied sheath, whichis compressed in the same manner against the channel walls.

The profile bodies may thus be introduced into the laying channel as anendless profile without any joints, the profile bodies expediently beingbrightly coloured, so that they simultaneously provide a warning forsubsequent roadworks. Moreover, the microcable is elastically sealedtowards the top, so that the microcable is isolated from mechanicalloading (vibration). Using a profile body which completely encloses themicrocable provides a uniform radial pressure, with the result that thecable is aligned without stressing. Since the elongate profile bodieshold the microcable down uniformly, it is no longer possible for themicrocable to rise up due to inherent stressing of the same. Moreover,the microcable is not subject, during laying, to any longitudinalstressing, which could possibly lead to expansion or tensile stressingof the optical fibres. During the laying operation, the microcable isrouted very accurately, so that the cable cannot deflect or buckle underthe thermal or mechanical loading. Furthermore, pressing the profilebodies into the laying channel results in gap-free filling of theinterstices in the vicinity of the channel wall on account of theirelastic properties.

The microcable may have a sheath extruded on it as early as theproduction stage. However, it is also possible to apply a cylindricalsheathing subsequently, shortly before the microcable is laid, saidsheathing preferably being slit, so that it can be latched onto themicrocable.

The introduced profile bodies can be cut out in a simple manner, duringrepair work, with the aid of a chisel or knife, so that the microcablewhich is to be repaired can be lifted in a simple manner.

It is also possible for a plurality of microcables to be arranged oneabove the other in one laying channel, this providing the possibility ofusing a profile body which has a plurality of longitudinally directedfree ducts.

It is also possible for further microcables to be introducedsubsequently into a laying channel, in which case the profile body isfirst of all removed in order to provide space for the furthermicrocable. A profile body is then subsequently pressed in and is, onceagain, closed off towards the top with a sealant.

If use is made of relatively hard profile bodies, additional free ductsmay run in the longitudinal direction, it being possible for fibres tobe provided therein, for example blown in, at a later point in time.

FIG. 49 shows a laying channel VN in solid ground VG, for example a roadsurface. The microcable MK has already been introduced in the base ofsaid laying channel VN. As the arrow GK indicates, a continuous profilebody GU consisting of elastic material, for example rubber, has beenintroduced above the microcable MK as a holding-down device for thesame.

FIG. 50, then, shows that the action of pressing in causes the profilebody GU to mould to the microcable MK and the channel wall NW. The restof the laying channel is filled in a sealed manner towards the top, upto the road surface SO, with a sealant B, for example a hot-meltingbitumen.

FIG. 51 shows, schematically, the operation of a laying unit VW. Themicrocable MK is unwound directly from a drum TMK on the left-hand side,so that the microcable can be laid easily in the laying channel.Unnecessary deformation of the microcable is avoided in this case. Alaying shoe VS avoids the situation where the microcable MK rises up outof the laying channel. Provided on the right-hand side of the layingunit VW is a second drum TGU for the profile body GU which iscontinuously pressed into the laying channel VN above the microcable MRby a pressure-exerting roller AR. In this way, in a laying operation,the microcable KM is laid in the laying channel VN, and fixed by theprofile body, in a simple manner. The laying shoe VS is held in positionwith the aid of a spring structure F, and a braking device BR ensures adefined drawing-off speed for the two drums TMK and TGU. Finally, thelaying direction VR is indicated by an arrow.

FIG. 52 shows a microcable MK which has already been provided with anelongate, annular profile body GUR. This profile body can either beextruded onto the microcable MK during production or be drawn onsubsequently. If the profile body GUR is drawn on subsequently, it inexpedient to provide a longitudinal slit S, so that the profile body GURcan be latched onto the microcable MK by expansion. The edges of thelongitudinal slit S are expediently bevelled, to render the latching-onoperation easier.

FIG. 53 shows a laid microcable MK with a profile body GUR drawnthereon, the pressing-in operation deforming said profile body such thatcavities are largely eliminated. In this embodiment, furthermore, anadditional profile ZP which additionally closes off the laying channeltowards the top is introduced. The two profile bodies consist ofelastically or plastic material, so that they lend themselves well todeformation. The rest of the laying channel VQ is, once again, closedoff and sealed with a sealant, for example hot bitumen B. If it isintended to lift a microcable MR again, then a chisel is used to removethe sealant B mechanically and extract it from the laying channel. Sinceit is only the sealant and the channel wall which adhere firmly to oneanother, the profile body can be easily drawn out after removal of thesealant. As a result, the microcable MK which is to be repaired isfreely accessible again.

FIG. 54 shows the cross-section through an elongate profile body VPcomprising a solid profile which has elastic properties, but cannot bedeformed plastically. The profile body is fixed in the laying channel byelastic barbs WH. Arranged within the profile body VP are longitudinallyrunning free ducts FK into which fibres can be drawn or blown at a laterpoint in time. Provided in the upper region of the profile body VP is aduct for a microcable MK which is introduced into the profile body VP inthe direction GR, through a longitudinally running slit VPS, before thelaying operation.

FIG. 55 shows the profile body VP of FIG. 54 within the laying channelVN, the elastic barbs WE having been wedged along the channel wall.Additional optical waveguides may possibly be drawn or blown into thefree ducts FK of the profile body VP at a subsequent point in time. Theupper part of the laying channel VN is, once again, filled with asealant B.

FIG. 56 shows a cross-section of a profile body P which likewise haselastic properties, but cannot be deformed plastically and has alreadybeen sheathed at the factory with a fusible sealant BVP, for exampleconsisting of hot bitumen or hot-melt adhesive. This grooved mouldingNFT is heated before laying, so that it can be rolled into the layingchannel in the hot state. Free ducts are, once again, provided in theprofile body P, but a slit duct for receiving a microcable may also beprovided here.

FIG. 57 shows the laying operation for a grooved moulding NFT accordingto FIG. 56. Here, use is made of a hot roll WW which presses the heatedgrooved moulding NFT into the laying channel VN. The sealant sheathingthe profile body is expediently heated by heat radiation WS frominfrared radiators IS. Before laying, the laying channel VN is alsoheated in order to avoid overly rapid cooling of the sealant. Finally,the excess sealant is rolled in at the road surface and removed.

Furthermore, the object of one development of the invention is to find aprocess in which the laid minicable or microcable is sufficientlyprotected against damage by the penetration of pointed implements andvery sharp-edged objects. The said object is achieved according to theinvention, with the aid of a process for introducing an optical cable ofthe type mentioned in the introduction, in that, after the introductionof the minicable or microcable into the laying channel, an elastic,notch-impact-resistant covering profile which is difficult to cutthrough by mechanical intervention is laid in the longitudinal directionof the minicable or microcable, and in that the width of the layingchannel is covered in so doing.

The advantages of the process according to the invention for layingoptical-waveguide cables, in particular minicables or microcables,consists essentially in that as early as at the actual laying stageitself additional protection is afforded for the optical-waveguide cableagainst accidental or intentional mechanical intrusion into the layingchannel. Such intrusion in the route may occur, for example,deliberately as a result of vandalism or accidentally as a result ofwork being carried out in the ground there. Thus, for example, in thecase of the penetration of a pointed and very sharp-edged object, forexample a screwdriver or chisel, penetration as far as the microcable isprevented. This results in elastic/plastic deformation of the tough andresilient covering profile, which comprises, for example, a metal-wirecore and an elastic sheathing consisting of plastic material.Intermediate coverings which run directly above the microcable mayadditionally be introduced during the laying operation. Wires forreinforcing the mechanical strength and sensors for information which isto be called up may additionally be introduced into these intermediatecoverings. Such sensors may be used, for example, to locate and monitordisruption-free operation. The toughened resilient core essentiallyprevents the penetration with a sharp-edged object. The foam sheathing,on the other hand, cushions the additional loading and distributes thecompressed loading over a large surface area, so that the minicable ormicrocable is not deformed or damaged any further. In addition, thisalso provides a simple lifting aid for the optical-waveguide cable,since the tensile strength of the covering profile is sufficient forremoving from the laying channel the filling material which is locatedabove said covering profile. The covering profile also serves, at thesame time, as the holding-down device for the optical-waveguide cable inthe laying channel and, in the case of metal inserts, can also functionas an earthing strip.

FIG. 58 illustrates the cross-section of a laying channel VN, at thebase of which a microcable MK is laid. An intermediate covering ZWA isadditionally introduced, after or during the laying of the microcableMK, on said microcable MK located beneath it. This additionally producesbuffering against mechanical action from above, with the result thatdirected blows with a tool or similar pointed object cannot deform oreven cut through the microcable MK. Said intermediate covering ZWA may,if appropriate be provided with inserts ZWE, for example with metallicwires, or with sensors. Such sensors can be used at a later point intime to locate the cable routing as well as penetrating water ordisruptions in the road structure and to trace the intrusion. With anintermediate covering ZWA consisting of conductive material, it is alsopossible for the tube MKR of the microcable MK to be manufactured fromplastic instead of metal, it being necessary for the correspondingboundary conditions as regards tensile strength and transversecompressive strength to be observed. The covering profile AP on whichthe invention is primarily based is then likewise introduced above thisintermediate covering ZWA after or during the introduction of themicrocable. Said covering profile AP may, in principle, be designed as ametal-wire, plastic, hemp or sisal line, it being necessary for thematerial used to have the corresponding properties. This means that thecovering profile AP has to be designed so that it is difficult to cutthrough, can be deformed mechanically to a limited extent and is toughand resilient, which can be achieved, for example, by strandingindividual elements. However, it is advantageous if such an element iscoated, as core MFK, with an elastic sheathing APU, preferablyconsisting of foam material, it being necessary for the diameter of theoverall covering profile AP to correspond to the width of the layingchannel VN, such that clamping in the laying channel is also achievedtherewith. The core MFK itself has to have a thickness which correspondsat least to the diameter of the microcable, so that the covering profileAP with its core MFK provides the microcable MK with full coveredprotection. The rest of the laying channel VN is filled towards the top,towards the surface of the ground VG, with a filling material,preferably with hot bitumen. Such a covering profile AP thus providesconsiderable protection against accidental or intentional penetration ofdestructive objects into the laying channel VN, the tough and resilientcore MFK largely preventing the penetration of a sharp-edged object. Inthis case, the sheathing APU consisting of elastic material cushions theloading and distributes the compressive loading over a large surfacearea. The microcable MK located therebeneath is not deformed or damaged.However, the intermediate covering ZWA shown in this figure does nothave to form part of the arrangement if the covering profile AP meetsthe required conditions itself. Moreover, the mechanically strongstructure of the covering profile AP may also be used as a simplelifting aid for the microcable MK since, on account of the highmechanical strength, it can be used, if required, to draw out from thelaying channel VN the filling material FM located thereabove.

FIG. 59 illustrates assumed mechanical loading by a pointed object SGwhich is driven with a force P into the laying channel filled with thefilling material FM. In this operation, the filling material PM isdisplaced and the object SG comes into contact with the elasticsheathing APU of the covering profile AP. In this case, the sheathingAPU is deformed, or even cut through, but the pointed object SG thencomes up against the core MFK, which is difficult to cut through, of thecovering profile AP, where it is finally stopped. That side of thesheathing APU which is located therebeneath is deformed by the pressureproduced, and a distribution of pressure takes place. The microcable MKlocated therebeneath, which in this case is arranged beneath theintermediate covering ZWA, is thus not damaged.

FIG. 60 illustrates the operation according to FIG. 59 in cross-section.It can clearly be seen that, when it comes into contact with thecovering profile AP, the pointed object SG deforms, or else cutsthrough, the sheathing APU and is then prevented from advancing furtherby the core MFK, otherwise, the conditions correspond to FIG. 59.

1-122. (canceled)
 172. A fiber optic cable installation structurecomprising: a surface defining a channel having a width of about 12 mmor less; a cable disposed within the channel, said cable having at leastone optical waveguide disposed within a copper tube and a jacketsurrounding the copper tube, wherein the copper tube has a ratio of awall thickness to an external diameter, the ratio being in the range ofabout 0.2 to about 0.05; and a filling material overlying the cable andat least partially filling the channel, the filling material at leastpartially comprised of material not previously evacuated to form thechannel.
 173. The fiber optic cable installation structure of claim 172,wherein the cable has a diameter of about 10 mm or less.
 174. The fiberoptic cable installation structure of claim 172, wherein the surfacedefines the channel to have a width of about 7 mm or less.
 175. Thefiber optic cable installation structure of claim 172, wherein the cablehas a diameter of about 5.5 mm or less.
 176. The fiber optic cableinstallation structure of claim 172, wherein the surface defines thechannel to have a depth of about 15 cm or less.
 177. The fiber opticcable installation structure of claim 172, wherein the surface comprisesa solid surface selected from the group consisting of asphalt, concrete,road surface, curbstone, and stone slab.
 178. The fiber optic cableinstallation structure of claim 172, further comprising a releaseelement disposed within the channel and extending lengthwise along thecable, the filling material also overlying the release element.
 179. Thefiber optic cable installation structure of claim 172, wherein thefilling material is formed of a material selected from the groupconsisting of bitumen and a hot melt adhesive.
 180. The fiber opticcable installation structure of claim 172, further comprising ahold-down device, the hold-down device disposed within the channel forholding the cable within the channel.
 181. A fiber optic cableinstallation structure comprising: a surface defining a channel; a cabledisposed within the channel, the cable comprising a copper tube and atleast one optical waveguide disposed within the tube; a hold-downdevice, the hold-down device disposed within the channel for holding thecable within the channel; and a filling material overlying the cable andthe hold-down device and at least partially filling the channel. 182.The fiber optic cable installation of claim 181, the copper tube havinga ratio of a wall thickness to an external diameter, the ratio being inthe range of about 0.2 to about 0.05
 183. The fiber optic cableinstallation structure of claim 181, wherein the surface defines thechannel to have a width of about 12 mm or less and the cable has adiameter of about 10 mm or less.
 184. The fiber optic cable installationstructure of claim 181, wherein the surface defines the channel to havea width of about 7 mm or less and the cable has a diameter of about 5.5mm or less.
 185. The fiber optic cable installation structure of claim181, wherein the surface defines the channel to have a depth of about 15cm or less.
 186. The fiber optic cable installation structure of claim181, wherein the surface comprises a solid surface selected from thegroup consisting of asphalt, concrete, road surface, curbstone, andstone slab.
 187. The fiber optic cable installation structure of claim181, wherein the filling material is formed of a material selected fromthe group consisting of bitumen and a hot melt adhesive.
 188. A fiberoptic installation structure comprising: an elongate body defining atleast one lengthwise extending copper duct disposed within a channeldefined by a solid surface, wherein the channel has a depth of about 15cm or less; at least one optical waveguide disposed within at least onelengthwise extending copper duct defined by the elongate body; and afilling material overlying the elongate body and at least partiallyfilling the channel.
 189. The fiber optic installation structure ofclaim 161, wherein the elongate body is sized to fit within the channelhaving a width of about 12 mm or less.
 190. The fiber optic installationstructure of claim 161, wherein the elongate body is sized to fit withinthe channel having a width of about 7 mm or less.
 191. The fiber opticcable installation structure of claim 161, wherein the solid surface isselected from the group consisting of asphalt, concrete, road surface,curbstone, and stone slab.